In software development, the codebase is the set of source code files from which the end product is created. The process of creating the end product, which can also be referred to as building the end product or a build, may vary based on the type of codebase. For example, the end product may be created by compiling and linking the source code files or by arranging and packaging the files into a package that is later executed by an interpreter. What should be understood is that the functionality of the end product is defined by the code base.
When changes to the end product are needed (e.g. new features, bug fixes, etc.), software developers make changes to the files of the codebase. In many cases, the software developer will group all the desired changes for submission to the code base in what is called a commit. The codebase may pick up the commit and include the changes the developer made in the next build of the end product.